1. Field of the Invention
This invention relates to a display touch type information input system for inputting operating information by detecting the touching of a switch displayed on screen.
2. Prior Art
Heretofore, radio sets, audio sets, air conditioners and many other accessory units which have no direct bearing on the running of vehicles have been mounted in vehicles, and there is a trend for an increasing number of these accessory units. Among these accessory units are navigation units, and vehicles with navigation units mounted therein are increasing in number.
The navigation unit serves to assist driving by displaying the present location on a map, and there are many navigation units which undertake route guidance by displaying the route to a destination when the destination is input.
Such a navigation unit requires a display for the map display. In addition, various operations are necessary for the input of the destination and other purposes. However, the space available within a vehicle is limited, and it is impossible to provide exclusive switches for respective necessary operations. Usually, therefore, the display surface is utilized as a touch switch panel, that is, it is utilized as a switch. Also, there are many cases in which the same display is utilized as a switch for operating an air conditioner, an audio set, etc., thus dispensing with some of the dedicated switches.
There are many different types of touch switch panel, such as an electrostatic capacitance type, an optical type, etc. In many cases, however, irrespective of the type of touch switch panel used, the touch detection area is slightly above the actual display surface.
For example, in the electrostatic capacitance type, use is made of deformation of a film provided on the display surface, and in the optical type blocking of light beam provided along the display surface is detected. Therefore, the actual detection area is above the display surface. This leads to a problem that an error is produced between a switch displayed on the display and the actual detection position.
Particularly, in the optical type an acrylic acid resin sheet for screen protection and an LCF (light control film) for suppressing reflection of light by the screen surface are provided between the switch display on the screen and a detection light beam. The thickness thus provided constitutes a corresponding distance between switch display and reaction point. In the optical type, therefore, the problem noted above is particularly pronounced.
Meanwhile, the display that is provided in the vehicle can not be disposed right directly in front of the driver's seat. That is, it has to be disposed at an intermediate position between the driver seat and the passenager seat. Inevitably, therefore, the driver's eyesight is directed obliquely with respect to the display. This leads to an error between the switch display on the display and directly above the touch reaction point (shown shaded), as shown in FIG. 1, and it is impossible to obtain correct detection of the driver's point of touch.
Japanese Utility Model Publication No. 121641/1987 shows precluding the deviation between display switch and reaction area due to a deviation of the driver's eyesight direction by shifting a switch display position (i.e., the whole display on the screen) according to the operator's position. Particularly, in a system disclosed in this publication seating detection switches are provided on the driver and passenger seats, and the switch display position is shifted by specifying the operator from the status of the seating detection switches. More specifically, when the driver alone is present, the display position is shifted to the left, while when both the driver and a passenger are present it is held at the center.
In this prior art example, however, sufficient improvement is not made because what is done is merely to shift the display itself. For example, there is such a problem that when the system is operated with the driver's face brought to the front right of the display, sufficient reaction can not be obtained due to a display deviation.
Particularly, while the touch of the touch switch panel is detected with respect to a plurality of spaced-apart reaction points, the reaction points can not be arranged very closely. Therefore, where a plurality of switches are displayed, the switch display may be comparatively small, and the number of reaction points of the switch display may be considerably small. By way of example, where the area defined by reaction points and the shape of switch display are in accord as shown in FIG. 2, the effect of the eyesight deviation is not so much. However, there is a case when the switch display and reaction points are deviated as shown in FIG. 3. In this example, while switches a and b are equal in size, the switch a is constituted by two reaction points, while the switch b is constituted by four reaction points. In such a case, if the eyesight direction is oblique with respect to the switch a, there is a high possibility that reaction points which do not belong to the switch a are operated by the driver's finger. If this is the case, sufficient reaction can not be obtained.